Rock drill



W, A. SMITH.

ROCK DRILLA AP'PLICATIQM FILED weils; 1920.

Pafented Sept. 19,V N22.

lNvENToR Y Patented Sept. I9, i922. v liyiigww ultra etarras testeur eprice..

WILLIAM A. SMITH, `F PHILLIPSBURG, NEW' JERSEY, SSIGrNOR` T0 INGERSOLL- RAND COMPANY, OF JERSEY CITY, NEVI JERSEY, A CORPORATION OF NEW JERSEY.

ROCK DRILL.

Application filed August 13, 1920. Serial No. 403,357.

To all 107mmz't may concern.' shank O forms another forwardly driving 55 Be it known that I, WILLIAM A. SMITH, a surface constantly supplied with fluid prescitizen of the United States, a resident of sure in the smaller cylinder bore U. Phillipsburg, county of Warren, State of Fluid pressure is supplied to the rear endv New Jersey, have invented certain new and of the larger bore of the cylinder through useful Improvements in Rock Drills, of the passage V controlled by the piston shank 60 which the following is a specification, and communicating with the supply passage This invention relates to fluid actuated K in the back head. The main cylinder bore rock drills of the hammer type, but more is exhausted by means of the usual pisparticularly to rockdrill having a percuston controlled exhaust port W. l

sive element provided with an auxiliary Fluid pressure is supplied to the front 65 valve for controlling admission of fluid to end of the larger bore of the cylinder one end of the cylinder so that the passage through the forward supply passage X for conveying fluid, although ultimately conopening into the constant pressure chamber trolled by the piston, will remain open for formed by the smaller cylinder bore through a greater porton of the return stroke than the forward admission port Y adapted to be 70 of the forward stroke. 1 over-run by the piston shank on its forward Such a rock *drill is disclosed in U.' S. stroke and a second or rearward admission Patent No. 1,096,987 granted May 19, 19111:, port Z controlled by the valve a is provided Y .Y

to Lewis C. Bayles, and the object of the asin U. S. Patent No.1,096,987. The valve present invention is to provide means cona is subjected to the fluctuating pressure in 7 5 trolled by the valve mentioned. Yfor relieving passage X on one operative surface Zi and is compression at one or both ends of the subject on an opposed operative surface stroke, in order to incorporate the anti-comto the fluctuating pressure behind the main pression feature which proves advantagepiston head L through the passage l comous with a rock drill cf this type in cermunicating with the rear end of the larger 80 tain classes of work. cylinder bore.

To these ends the invention is shown in The ,rearward admission port Z is so one of its preferred forms in the accomplaced that. it is uncovered by the piston panying drawings, in whichsoon after the piston has passed the median Figures 1 and 2 are diagrammatic longipoint of its forward stroke. The forward 85 tudinal sectional elevations of a rock drill admission port Y is not uncovered until the embodying the invention, showing the pispiston is practically at the forward end of ton hammer in two different positions. its stroke.

Referring to the drawings, the cylinder A In this instance anti-compression or remay be provided with a front head B to reliever ports e and f are shown for the for- 90 ceive the drill steel C, and the impact blows ward and rearward ends of the main cylinder of the piston hammer D in this instance are bore Q., communicating with the valve chamreceived upon the anvil block E guided in ber g of the valve a by means of the pasthe anvil block holder F. The usual back sages 7L and respectively, and the valve is head G is provided with the inlet H and provided with the heads lo and 0 for con- 95 passages J and K for distribution of motive trolling communication between said antifluid. compression ports and the atmospheric port The piston D is of the differential type p. Either or both of said anti-compression having a main head L and a shank O of ports may be provided as desired.

smaller diameter connected to the head L In the operation of the machine, let it be by the reduced neck P. The main head assumed that the piston is at the end of its operates in the larger bore Q of the cylinrearward stroke and is starting forward as der and the front surface R and the rear in Figure 1. The valve a is in its forward 50 surface S of the head respectively form position, closing the rearward admission rearwardly and forwardly driving pressure port Z because the valve surface b is open to surfaces, in this instance intermittently supatmospheric pressure through the passage plied with iuid pressure in the ends of the X and exhaust port W. No fluid will be larger bore Q. The rear surface T of the admitted into the front end of the larger cylinder bore until the rear surface T of the piston shank has uncovered the forward admission port Y, which will admit fluid pres-y sure to the passage X, and throw the valve to its rearward position shown in Figure 2, because the pressure on the surface C of the valve has been relieved, ythus opening the rearward admission port Z and permitting fluid to pass to the forward end of the cylinder through both ports Y and Z, as the port Z is not covered by the piston shank until the lpiston has traveled a. considerable part of its `rearward stroke. The admission to the forward end of the cylinder will thus continuel for a considerably longer period during the backward 'stroke of the piston than during'the forward stroke. v

The object of this construction is that although the fluid is admitted to the forward end of the cylinder through the port Z for vthe same period of thefb'ackward stroke as it would be if there'wereno valve a and thus a full return stroke of the piston is obtained Z so that the machine operates even more efficiently under certain conditions of work.

I claim: Y

In a fluid operated rock drill of the hammer type7 thezcombination of a cylinder andrdifferential piston having two surfaces for driving it forwardly and one surface for driving it rearwardly, means 'for constantly supplying' fluid pressure to one of the forwardly driving pressure surfaces, passages controlled by the piston for admitting and exhausting` pressure in the cylinderV to exert an intermittent pressure on the other of the forwardly driving pressure surfaces, means for exerting intermittent pressure on the rearwardly driving pressure surface including a forward supply passage opening into therearward end of the cylinder through a forward admission port controlled by the piston, anti-compression ports for 'relieving compression in the' intermittently supplied portions of the cylinder and a Huid actuated valvecontrolling'a rearward admission port and the supply of fluid through said forward supply rpassage to the rearwardly drivingv pressure surface and also controlling com 1 munication between the saidxanti-compression ports and the atmosphere, said 'valve having operative surfaces exposed tothe pressure on said intermittently supplied surfaces.

- In testimony whereof I have signed this specification.

WILLIAM A, sMi-TH. 

